New study may show the cause of H1N1-triggered narcolepsy

A new study from Stanford University School of Medicine shows that in genetically susceptible people, narcolepsy can sometimes be triggered by a similarity between a protein called hypocretin and a portion of a protein from the pandemic H1N1 virus.

The study provides some of the most compelling evidence so far for a scientific concept called â€œmolecular mimicry.â€ Mimicry is the idea that the normal immune response to a pathogen, in this case the pandemic 2009 H1N1 influenza virus, can trigger autoimmunity â€” when the immune system mistakenly attacks healthy components of the body â€” because of similarity between a pathogen protein and a human protein.

â€œThe relationship between H1N1 infection, vaccination and narcolepsy gave us some very interesting insight into possible causes of the condition,â€ said Emmanuel Mignot, MD, PhD, professor of psychiatry and behavioral sciences, and chair of Narcolepsy Network’s Medical Advisory Board. â€œIn particular, it strongly suggested to us that T cells of the immune system primed to attack H1N1 can occasionally also cross-react with hypocretin and somehow cause the destruction of hypocretin-producing neurons.â€

The new study suggests new ways to try and intervene before complete destruction of hypocretin cells. The study also could lead to a new blood test to diagnose narcolepsy, and it sheds light on a previously observed association between a pandemic H1N1 vaccine used in Europe in 2009 and an increase in narcolepsy cases in Scandinavia the subsequent year.

Mignot, a narcolepsy researcher and director of the Stanford Center for Sleep Sciences and Medicine, shares senior authorship of the research with Elizabeth Mellins, MD, an immunology researcher and professor of pediatrics at Stanford. The study was published Dec. 18 in Science Translational Medicine. Postdoctoral scholars Alberto de la HerrÃ¡n-Arita, MD, PhD, and Birgitte Kornum, PhD, share lead authorship of the study.

â€œThis study will shape the next decade of research into narcolepsy. It will focus investigators on immune-mediated mechanisms of neuronal death, which ultimately may shed light on other autoimmune diseases, particularly of the brain,â€ Mellins said.